Apparatus and method of utilizing thermal energy using multi fluid direct contact hydraulic cycles

ABSTRACT

Apparatus for extracting useful work or electricity from low grade thermal sources comprising a chamber, a source of heated dense heat transfer fluid in communication with the chamber, a source of motive fluid in communication with the chamber, wherein the motive fluid comprises a liquid phase, a flow control mechanism cooperating with the source of heated dense heat transfer fluid and with the source of motive fluid to deliver said fluids into the chamber in a manner that said fluids come into direct contact with each other in the chamber to effect a phase change of the motive fluid from liquid to gas to increase the pressure within the chamber to yield pressurized fluids, and a work extracting mechanism in communication with the chamber that extracts work from the pressurized fluids by way of pressure let down.

FIELD OF THE INVENTION

The present invention relates to systems and methods for convertingthermal energy into useful products such as mechanical work, electricityor space heating. More particularly the present invention pertains tothe field of clean power production and an emission-less powerextraction system for use in converting thermal energy into electricityfrom sources such as solar, wind, waste heat, geothermal, biomassoxidation.

BACKGROUND OF THE INVENTION

There are numerous industrial and other processes that produce wasteheat in the approximate range of 34° F. to 210° F. In addition, heat inthese low grade thermal ranges may also be obtained from geothermalsources, including man-made geothermal sources such as those occurringin abandoned oil and natural gas wells, as well as natural water bodies(oceans, lakes, rivers), solar and wind sources. Heat in this range isdifficult to utilize since it too low to be used in conventional Rankincycle or other vapor cycles to generate useful energy. Accordingly,there is a need for a more efficient method of extracting useful workand electricity from low grade thermal sources.

SUMMARY OF THE INVENTION

The invention comprises methods and systems for utilizing two or morefluids in combination with each other where the fluids differ indensity, specific heat capacity and phase change properties. wherein atleast one of the fluids experiences a phase change at lower temperaturesand has a low specific gravity, referred to herein as the motive fluid(MF), and wherein at least one of the fluids has a high specificgravity, a high specific heat capacity and does not experience phasechange at the upper temperature range of the cycle operating profile,referred to herein as the dense heat transfer fluid (DHTF). The methodutilizes flows and processes in which two or more fluids are placed indirect contact with each other in a chamber, resulting in a dramaticexpansion of the motive fluid as it changes phase from liquid to vaporat relatively low temperatures as it absorbs energy from the dense heattransfer fluid, which experiences a reduction in temperature and remainsin a liquid state. The phase change from liquid to vapor of the motivefluid produces a large volume increase with a corresponding pressureincrease, which can then be sent to the inlet of various mechanicalextractions machinery suitable for conversion of the pressurized vaporflow to useful work.

Another key feature of utilizing fluids that differ in phase changetemperatures and specific gravity/density is that due to differingdensities in both liquid and vapor states, the motive fluid does notremain mixed with the dense heat transfer fluid and quickly experiencesgravity separation when combined/contained in the same space orcontainer. This density or gravity separation characteristic allows fordirect contact heat transfer, eliminating costly heat exchangers andresulting in faster heat transfer performance and thereby higher overallsystem efficiencies than a single fluid system. Also, the dense heattransfer fluid does not change phase during the exchange and thereforedoes not require cooling after the power extraction while stillproviding the hydraulic mass flow for power extraction. In contrast, themotive fluid volumes, which have changed phase from liquid to vapor andrequire condensing to return to liquid phase, make up a much smallerpercentage of the overall mass-flow and serve to provide only the volumechange function of the mass flow. This split between the motive fluidvolumes and the dense heat transfer fluid volumes requires less heatrecuperation/cooling and parasitic loads associated with condensing ofall fluids, resulting in greater efficiencies and the ability to createsubstantial amounts of useful work from very low temperature heatsources.

In one aspect the present invention provides an apparatus for extractinguseful work or electricity from low grade thermal sources comprising: achamber; a source of heated dense heat transfer fluid in communicationwith the chamber; a source of motive fluid in communication with thechamber, wherein the motive fluid comprises a liquid phase; a flowcontrol mechanism cooperating with the source of heated dense heattransfer fluid and with the source of motive fluid to deliver saidfluids into the chamber in a manner that said fluids come into directcontact with each other in the chamber to effect a phase change of themotive fluid from liquid to gas to increase the pressure within thechamber to yield pressurized fluids; and a work extracting mechanism incommunication with the chamber that extracts work from the pressurizedfluids by way of pressure let down.

As used herein, “chamber” means an enclosed cavity of any shape ordimension suitable to provide a static fixed volume or a moving fixedvolume capable of volumetrically limiting the motive fluid as itcombines with the dense heat transfer fluid and as the mixture expandsto motive fluid gaseous phase thereby creating an increase in pressurein the enclosed cavity.

In some embodiments, apparatus may further comprise a density separatordownstream of the work extracting mechanism to separate the dense heattransfer fluid from the motive fluid.

In some embodiments, apparatus may further comprise a condenserdownstream of the work extracting mechanism to condense the motive fluidinto liquid phase.

In some embodiments, apparatus may further comprise a firstrecirculating conduit to the source of motive fluid.

In some embodiments, apparatus may further comprise a secondrecirculating conduit to recirculate the dense heat transfer fluid tothe source of heated dense heat transfer fluid.

In some embodiments, apparatus may further comprise a heat exchangercommunicating with a thermal source and the second recirculating conduitto transfer heat energy from the thermal source to the dense heattransfer fluid to provide the source of heated dense heat transferfluid.

In some embodiments, the flow control mechanism may comprise a rotaryvalve having a first pocket to receive a volume of heated dense heattransfer fluid and a second pocket to receive a volume of motive fluid,the rotary valve being operable to expose the first pocket and thesecond pocket to the chamber to bring said fluids into direct contact.

In some embodiments, the work extracting mechanism may comprise aturbine that is driven by the pressurized fluids to rotate an outputshaft to produce work.

In some embodiments, the work extracting mechanism may comprise areciprocating piston that is driven by the pressurized fluids to rotatean output shaft to produce work.

In another aspect, the present invention provides a method of extractinguseful work or electricity from low grade thermal sources comprising thesteps of: heating a dense heat transfer fluid using heat from a thermalsource; mixing the heated dense heat transfer fluid with a motive fluidcomprising a liquid phase in a chamber to effect a phase change of themotive fluid from liquid to gas to increase the pressure within thechamber and yield pressurized fluids; and using the energy of thepressurized fluids to produce useful work.

In some embodiments, the dense transfer fluid may be heated in step a.to a temperature of about 34° F. to about 210° F.

In some embodiments, the method may further comprise the step of coolingthe motive fluid after step c. to effect a phase change of the motivefluid to liquid.

The embodiments described herein employs CO₂ or various organic fluidssuch as R134a or R290 as the motive fluid, and fluids such as EthyleneGlycol or Glycerol as the dense heat transfer fluid. However, it will beapparent from the disclosure herein that other fluids may be used as themotive fluid and the dense heat transfer fluid.

Heat energy for use with the invention may be collected and stored in athermal storage system comprising of an insulated storage container,where thermal energy in a range from about 80° F. to about 210° F. istransferred to the water from a variety of thermal sources such assolar, wind to thermal, geothermal, waste heat from mobile or stationaryprocesses, or in some cases, the oxidation of bio-mass.

The foregoing was intended as a broad summary only and of only some ofthe aspects of the invention. It was not intended to define the limitsor requirements of the invention. Other aspects of the invention will beappreciated by reference to the detailed description of the preferredembodiment and to the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features of the invention will become more apparent fromthe following description in which reference is made to the appendeddrawings and wherein:

FIG. 1 is a process flow diagram of an emission-less power extractionsystem utilizing the Multi Fluid Direct Contact Pulsating Cycle for theconversion of thermal energy into electricity from sources such assolar, wind, waste heat, geothermal, biomass oxidation according to thepresent invention.

FIG. 2 is a detailed representative view of one accumulator during theDischarge phase of the cycle according to the present invention takenfrom a side profile view.

FIG. 3 is a detailed representative view of one accumulator during theRecharge phase of the cycle according to the present invention takenfrom a side profile view.

FIG. 4 is a process flow diagram of another embodiment of anemission-less power extraction system utilizing the Multi Fluid DirectContact Pulsating Cycle for the conversion of thermal energy intoelectricity from sources such as solar, wind, waste heat, geothermal,biomass oxidation according to the present invention.

FIG. 5 is a detailed representative view of a piston expander methodduring the power stroke of the cycle according to the present inventiontaken from a side profile view.

FIG. 6 is a detailed representative view of a piston expander methodduring the exhaust stroke of the cycle according to the presentinvention taken from a side profile view.

FIG. 7 is a process flow diagram of an emission-less power extractionsystem utilizing a multi fluid direct contact continuous cycle for theconversion of thermal energy into electricity from sources such assolar, wind, waste heat, geothermal, biomass oxidation according to thepresent invention.

FIG. 8 is a process flow diagram of an emission-less power extractionsystem in accordance with another embodiment of the present inventionemploying an external high-pressure rotary injection valve inconjunction with a rotary turbine.

FIG. 9, is a process flow diagram of an emission less power extractionsystem in accordance with another embodiment of the present inventionemploying an external high-pressure rotary injection valve inconjunction with a piston expansion engine.

FIG. 10 is an end view of an external high-pressure rotary injectionvalve in the filling phase of its rotation.

FIG. 11 is an end view of an external high-pressure rotary injectionvalve of FIG. 10 in the injection phase of its rotation.

FIG. 12 is an end view of an external high-pressure rotary injectionvalve of FIG. 10 in the exhaust phase of its rotation.

FIG. 13 is an end view of an external high-pressure rotary injectionvalve of FIG. 10 showing one example of three possible positions in thecycle where the fluid pockets are isolated or sealed from anycommunication or flow.

FIG. 14 is an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander in the exhaust andpocket fill phase of the rotational cycle.

FIG. 15 is an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander of FIG. 14 in the powerphase of the rotational cycle.

FIG. 16 is an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander of FIG. 14 in thepower/expansion phase of the rotational cycle.

FIG. 17 is an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander of FIG. 14 in thebeginning of the exhaust and pocket fill phase of the rotational cycle.

DETAILED DESCRIPTION

An embodiment of the present invention for the conversion of thermalenergy into electricity from sources such as solar, wind, waste heat,geothermal, biomass oxidation, referred to herein as a multi fluiddirect contact pulsating cycle (motive fluid-DCPC), is shown in FIG. 1.The present invention may extract useful work from any thermal sourcecapable of being delivered at temperatures between 80° F. to 210° F.More specifically, the present invention may be used to extract usefulwork form thermal sources such as solar, wind, waste heat, geothermal,biomass oxidation, and others.

Referring to FIGS. 1-3, the illustrated embodiment of the multi fluiddirect contact pulsating cycle is shown comprising three sealed chambersor accumulators 5, into each of which is provided a metered flow ofmotive fluid via conduits 23, and a metered flow of dense heat transferfluid via conduits 4. Control of the fluid flow is accomplished byvalves 24 and 6, respectively. In general terms, each accumulator 5 isprovided with a volume of “hot” dense heat transfer fluid into which isinjected a volume of “cold” motive fluid. Heat is transferred from thedense heat transfer fluid to the motive fluid, which rises to the topand undergoes a volume expansion as it changes phase from a liquid to agas. This volume expansion within the confined space of the accumulator5 increases the pressure within the accumulator, and upon the timedrelease of valves 7 on the bottom of the accumulator a volume of denseheat transfer fluid is forced under pressure through an expander such ashydraulic motor 9, in which the flow of the dense heat transfer fluid isconverted to useful work. After passing through the hydraulic motor 9,the “cooled” dense heat transfer fluid may be stored if necessary inreservoir 1 and is reheated in heat exchanger 3 utilizing heat from theheat source, and then recirculated into the accumulator 5 to rechargethe accumulator for the cycle to repeat.

After the heating and the expansion of the motive fluid, the motivefluid in the gas phase (or mixed gas-liquid phases) is allowed to ventedout of the top of the accumulator by opening valves 14 as the level ofthe dense heat transfer fluid rises during the recharge phase, and themotive fluid passes through conduit 16 to a condenser step 19 where themotive fluid is cooled and condensed back to a liquid phase, after whichit is directed via conduit 22 into conduits 23 for injection back intothe accumulators 5 for the cycle to repeat.

With reference to FIGS. 2-4, aspects of the present invention aredescribed in more detail in reference to an embodiment shown illustratedin FIG. 4.

Multi-Fluid Flow and Pulsation Features:

A critical feature of the multi fluid direct contact pulsating cycle isin the unique employment of two or more fluids, varying in density andphase change characteristics, in a 3-step power cycle involving threedistinct thermal and pressure stages:(1) Re-charge; (2) Ready and (3)Discharge. These three stages result in a ‘pulsating’ flow to thehydraulic motor/expander unit(s). For example, in the case of a threechamber and one hydraulic expander system as described herein, onechamber is in re-charge mode, one is in discharge mode, and one is inready mode. A programmable logic controller (PLC) or other controllermanages the timing of the valving to cycle effectively for coordinatingthe three steps taking place in each of the chamber units oraccumulators 5 as needed to provide a steady flow of hydraulic fluid tothe hydraulic expander. This pulsating characteristic results in theexpander seeing a gentle swinging pressure gradient ranging from thehigh pressure of the cycle to the low pressure of the cycle—in this case2000-3000 PSI to 350-650 PSI, an average in this example of 1500 PSI atthe inlet to the hydraulic motor/expander. This pulsation characteristicalso results in a corresponding pulsation of power output from thehydraulic expander output shaft. To accommodate this unique feature, thesystem employs DC generators sending DC electrical energy to DCbatteries which are not negatively affected by the pulsationfeature—which appears as a wave of amperage at a set voltage (controlledby a voltage regulator which looks at the shaft RPM and increases ordecreases the load on the Alternator windings as needed to maintain thetarget voltage as well as the shaft rpm). AC current is then drawn fromthe DC batteries via standard inverter equipment thereby delivering avery high quality AC power to the end use.

The three distinct and separated thermal and pressure stages: A.Re-charge; B. Ready; and C. Discharge are further described withreference to FIGS. 2-4.

A. During the Re-charge phase dense heat transfer fluid is moved againstcondenser 18 vapor pressure, 350 psi-650 psi, from reservoir 1 by pump2, passing through heat exchanger 3 and is heated to the targettemperatures required, in this case approximately 140° F. The dense heattransfer fluid continues via header 4 to enter the bottom of one ofthree accumulator chambers 5 via a valve 6. The hot dense heat transferfluid flows into the accumulator 5 until the desired level is reachedwhich is controlled by valve 6 in reaction to level sensors placed atthe appropriate elevation in the accumulator 5 and a PLC.

Also during the re-charge step, as the level of the dense heat transferfluid rises in the accumulator 5 the motive fluid is displaced from theaccumulator 5 at condenser 18 vapor pressure levels, in this caseapproximately 350-650 psi, and exits the top of the chamber via valve 14and travels via conduit 16 through recuperator 17 and into condenser 18where it is cooled adequately to return to a liquid phase.

B. During the Ready step liquid phase motive fluid flows from condenser18 via conduit 20 into pump 21 where it is pressurized initially tocondenser 18 pressures and then flows via conduit 22 to one of theconduits 23 via a valve 24 which is controlled by the PLC. On passingone of the valves 24 the motive fluid enters accumulator 5. During thisstep, a very controlled amount of liquid motive fluid is injected atpressures from condenser 18 pressures into the accumulator 5 where themotive fluid comes into direct contact with the hot dense heat transferfluid, absorbs thermal energy causing a phase change from liquid tovapor which in turn causes the pressure to increase in the accumulatorto the desired level of approximately 1500 psi. At this point theaccumulator is ready to go to the discharge step.

C. During the Discharge or power step one of valve 7 are opened allowingdense heat transfer fluid to flow via conduit 8 at high pressures intohydraulic motor 9. Work is extracted from the dense heat transfer fluidby the hydraulic motor which in turn drives an electrical generator 10.The dense heat transfer fluid, now slightly cooled and at condenser 18pressures exits the hydraulic motor 9 via conduit 12 and entersreservoir 1 from where it can further continue to the re-charge step ofthe circuit. Simultaneously the motive fluid is pumped from condenser 18via conduit 20 by pump 21. motive fluid is compressed to dischargesystem pressure by pump 21 and flows via conduit 22 into one of conduit23 and through valve 24 and into accumulator 5. Upon entering theaccumulator, the motive fluid comes into contact with the hot dense heattransfer fluid effectively absorbing thermal energy and experiencingrapid phase change. Due to the density difference between the motivefluid vapor and the dense heat transfer fluid the motive fluid vaporrapidly moves upward in the accumulator column arriving at the top ofthe accumulator where it continues to expand to its vapor pressure atthe temperatures present in the accumulator, effectively creating adownward force on the dense heat transfer fluid column. Due to thispressure the dense heat transfer fluid is forced downward and out thebottom of accumulator 5. Over the duration of the pulse a minimum levelis reached in the accumulator 5 required to maintain a fluid seal whichensures that none of the motive fluid exits the bottom of theaccumulator and into the hydraulic motor 9. This minimum dense heattransfer fluid level is controlled by level sensors and the PLCactuating a valve 7. The downward flow of high pressure dense heattransfer fluid travels via valve 7 and conduit 8 and into hydraulicmotor 9 to produce useful work as described above. The motive fluid flowis precisely controlled by valve 24 via a PLC to inject only thenecessary liquid volume of motive fluid needed, which when changed tovapor, provides the desired downward motive force/pressure to the denseheat transfer fluid column. The discharge step ends with valve 7 closedwith the accumulator at or slightly above condenser 18 pressures and thevolume being substantially made up of motive fluid at vapor phase andvapor pressure with a suitable layer of dense heat transfer fluidremaining at the bottom of the accumulator acting as a barrier or sealpreventing any motive fluid vapor from exiting the accumulator andentering hydraulic pump 9.

The above 3 steps continue in a rotation on each of the 3 accumulatorswhereby the cycle from re-charge, ready, discharge continues in asequence controlled by the PLC providing a constant pulsating flow ofhigh pressure hydraulic fluid to the expander 9 to drive the electricgenerator 10. Work is extracted via a work extracting mechanism thatextracts work from the pressurized fluids by way of pressure let down,in this case, the expander 9.

Energy Recovery Feature:

The system described in FIG. 4 employs a closed loop refrigerationcircuit to effectively recover the energy from the discharged and warmvapor phase motive fluid during the process of condensing the motivefluid in condenser 18. Refrigerant such as R134a is compressed adequatepressures to produce the required temperature profile, approximately140° F., or the exchange of energy between the refrigerant and thesystem energy storage fluid contained in reservoir 30, in this case awater/glycol mixture. Compressed and hot refrigerant is conveyed by pump26, traveling via conduit 27 to heat exchanger 28 where the refrigerantis cooled effectively transferring its heat energy to the energy storagefluid. It continues via conduit 27 to Pressure Reduction Valve (PRV) 29where its pressure is reduced to approximately 25 psi with correspondingdrop in temperature to approximately 6° F. The refrigerant thencontinues into heat exchanger 25 located in the motive fluid condenser18 where it absorbs energy from the vapor phase motive fluid. Therefrigerant then travels via conduit 31 to recuperate 17 through heatexchanger 32 where it is further heated by the incoming vapor phasemotive fluid. The refrigerant, now ‘thermally loaded’ continues to theinlet of compressor 26 whereby it is compressed to approximately 150-200psi causing a increase in temperatures, to approximately 140° F.,providing an adequate temperature delta for transfer of thermal energyfrom the refrigerant into the energy storage fluid contained inreservoir 30. This completes the energy recovery cycle.

Thermal Energy In:

Thermal energy enters the system by the flow of heat water/glycol intoreservoir 30 at approximately 180° F. which is heated by an outsidesource such as solar, thermal wind-mills, geothermal, and the like, andenters the thermal storage reservoir 30 via inlet 33 and exits viaoutlet 34.

FIG. 2 shows a detailed side view of an accumulator 5 during thedischarge step. During the discharge step motive fluid enters theaccumulator 5 via conduit 23 through valve 24. As the liquid motivefluid enters the accumulator it comes into direct contact with the hotdense heat transfer fluid resulting in rapid phase change of the motivefluid from liquid to vapor. The low-density motive fluid vaporimmediately rises to the top of the accumulator column providing vaporhead and the motive pressure needed to force the dense heat transferfluid out the bottom of the accumulator via valve 7 and into hydraulicmotor 9 for the production of useful work.

FIG. 3 shows a detailed side view of an accumulator during the re-chargestep. dense heat transfer fluid is pumped into the bottom of accumulator5 via conduit 23 and through valve 24 which is controlled by system PLC.As the level of the incoming dense heat transfer fluid rises, the motivefluid is forced out the top of the accumulator through valve andconduit, traveling via conduit 16 through recuperator 17 and intocondenser 18, where it is cooled to liquid phase to continue into theReady and Discharge steps.

FIGS. 5 and 6 show an alternate energy extraction method in the form ofa reciprocating piston expander utilizing a closed piston chamber andvalving system much the same as an internal combustion engine withoutthe combustion.

FIG. 5 shows the power stroke where high pressure liquid motive fluidand hot dense heat transfer fluid are separately injected into thepiston chamber 34 via conduits 32 and 35 and valves 33 and 36. Valves 33and 36 open very briefly allowing a measured amount of the fluid mixtureinto piston chamber 34 adequate to allow for complete expansion of themotive fluid as the piston travels downward and useful work isextracted.

FIG. 6 shows the exhaust stroke where valves 33 and 36 are closed andvalve 38 allows the cooled and low pressure mixture of vapor phasemotive fluid and dense heat transfer fluid to exit via valve 38 andconduit 39. As the piston travels upward in the cylinder, the pistonchamber is reduced in volume forcing the low pressure vapor phase motivefluid and cooled dense heat transfer fluid mixture from the chamber. Thedischarged fluid mixture then continues via conduit 36 to a settlingreservoir where the heavier dense heat transfer fluid remains on thebottom of the chamber and the lighter motive fluid vapor is drawn offthe top of the settling chamber traveling on to a condenser where it iscooled and returned to a liquid phase to be pumped into valve 33 andinto the piston chamber 34 during the power stroke. The dense heattransfer fluid is drawn from the bottom of the settling chamber andtravels to a re-heater where its temperature is increased to the desiredlevel before it is re-injected via valve 36 in piston chamber 34 duringthe power stroke. This is a two-stroke internal expansion cycle takingplace at under 180° F. without combustion or exhaust to the environment.

FIG. 7 shows an alternate energy extraction method utilizing a constantflow approach method similar to a Rankine Cycle, Organic Rankine Cycleor Brayton Cycle, as opposed to a pulsating flow as described in FIG. 1above. Reservoir 41 contains dense heat transfer fluid 45 which travelsvia conduit 43 to pump 42 where it is pressurized to system pressure,approximately 500-1000 PSI as it travels to heat exchanger 46 where itis effective heated to desired temperatures by absorbing heat energyfrom the thermal storage fluid in reservoir 44. The dense heat transferfluid then continues via conduit 48 to blend chamber 49 where it isblended with incoming motive fluid from conduit 53. Liquid motive fluidis pumped from condenser 51 by pump 52 and travels via conduit 53 tomixing chamber 49 where it comes into direct contact and effectively‘mixes’ with the hot dense heat transfer fluid coming from conduit 48and pump 42. Upon contact the motive fluid rapidly expands to vaporphase as it absorbs thermal energy from the hot dense heat transferfluid. Upon expansion, the now mixed-phase combined flow vapor motivefluid and liquid dense heat transfer fluid mixture continues into theinlet of expander/turbine 55 via conduit 54. Expander 55 converts thehigh pressure multi-phase flow to useful work by driving electricalgenerator 56. The fluid mixture then exits the expander 55 in a cooledbut substantially multi-phase condition with the motive fluid beingvapor and the dense heat transfer fluid being liquid. The mixturecontinues via conduit 57 into separation chamber 45. The motive fluid,being in vapor phase and significantly lighter than the dense heattransfer fluid, remains at the top of the chamber and continues viaconduit 58 into condenser 51 where it is cooled and returned to liquidphase before continuing on the high-pressure side of the circuit. Thedense heat transfer fluid is drawn off the bottom of settling chamber 45and is then compressed by pump 42 to system pressure and continues viaconduit 43 to the heat exchanger 46 where it is heated to the desiredtemperature and then continues on to the high pressure side of thecircuit and the mixing chamber 49 via conduit 48.

Referring to FIG. 8, there is shown a process flow diagram of anemission-less power extraction system in accordance with anotherembodiment of the present invention system utilizing a multi fluiddirect contact pulsating cycle and employing an external high-pressurerotary injection valve in conjunction with a rotary turbine for theconversion of thermal energy into electricity from sources such assolar, wind, waste heat, geothermal, biomass oxidation according to thepresent invention.

The unique function of the high-pressure rotary valve as describedherein allows for fluids to be injected, without the use of auxiliarypumping equipment, into enclosed spaces such as a piston bore in areciprocating engine; the inlet to a rotary machine such as a Turbine orSliding Vane Rotary motor, and the like, where high pressure workingfluid expansion can take place producing useful work extraction withoutthe use of auxiliary pumping equipment along with the undesirableparasitic loads necessary in Rankine or Organic Rankine type systems.

Thermal energy is supplied to the system via a thermal energy carrierfluid, which could be water, air, thermal oil, or other fluid sources ofheat energy. The thermal energy carrier fluid source may be from astorage container (not shown) or it could be a continuous source. Thethermal energy carrier fluid is circulated through a heat booster 72 viaan inlet 71 and an outlet 70. The heat booster 72 may be a heatexchanger commercially available such as a shell and tube or a brazedplate exchanger such as those sold by companies such as Danfoss. Theheat booster 72 includes a heat exchanger coil 73 through which thethermal energy carrier fluid circulates on one side to transfer heatenergy to the dense heat transfer fluid that circulates on the otherside.

A flow control mechanism such as rotary valve 64 is driven and speedcontrolled by drive motor 78 and effectively moves fluid pockets 105 and106 (see. FIGS. 14-17) through three distinct cycles, each of which seefluid pockets 105 and 106 sealed off from the other ports in the valvebody. Firstly, as drive motor 78 rotates the valve, fluid pockets 105and 106 rotate to become aligned only with inlet ports 79 and 80. Uponalignment motive fluid enters and fills fluid pocket 105 and dense heattransfer fluid enters and fills fluid pocket 106. Secondly, as rotationcontinues, fluid pockets 105 and 106 are momentarily isolated from alloutlet ports as well as from each of pockets 105 and 106 by the a sealprovided by a lubricated contact between rotating valve body 64 andvalve body housing 112 (which operate as a air-bearing which is commonlyknow in the industry and as sold by companies such as Neway AirBearings). As rotation continues the fluid pockets come into alignmentonly with inlet ports 69 allowing the contents of pockets 105 and 106 tobe released into expansion chamber 77 causing a rapid thermal reactionbetween the motive fluid and the dense heat transfer fluid with acorresponding pressure increase in expansion chamber 77. Thirdly,rotation continues to momentarily seal fluid pockets 105 and 106 frominlet ports 69 and expansion chamber 77 and, as rotation continues, tobecome aligned only with low pressure equalization ports 81 and 82allowing fluid communication of fluid pockets 105 and 106 with densityseparation chamber 91 allowing all residual volume of mixed motive fluidand dense heat transfer fluid remaining in fluid pockets 105 and 106 totravel to density separation chamber 91 effectively re-setting thepressure in fluid pockets 105 and 106 to the low pressure side of thecycle and ready to be recharged. The cycle continues through the threemain steps with sealing/isolation taking place between each position dueto the air bearing or lubricated seal between rotary valve 64 and valvehousing 112 as described above preventing the motive fluid and denseheat transfer fluid from directly entering expansion chamber 91 or thehigh-pressure mixture of motive fluid and dense heat transfer fluidproduced upon contact in expansion chamber 91 from exiting through theequalization ports 81 and 82. Delivery of the desired amount of volumeof dense heat transfer fluid and motive fluid for a target mass flow orpower output can be varied and controlled by adjusting the RPM of therotary valve spool which is driven by motor 78 which would be controlledby a industry standard PLC system via a variable frequency drive (VFD)drive to motor 78 as well as the diameter and length of the rotary valvespool as well as the size of the fluid pockets 105 and 106.

Dense heat transfer fluid is pumped through the heat exchanger 73 in theheat booster 72 by hydraulic motor 75 where it picks up heat energy fromthe thermal energy carrier fluid. The dense heat transfer fluid is thenflowed through an accumulator 74 that absorb the pulsation caused by theopening and closing of the rotary valves as described. Accumulator 74may be a piston hydraulic piston accumulator or a hydraulic bladderaccumulator such as for example sold by Parker. After the accumulator74, the dense heat transfer fluid flows to inlet 80 and then to fluidpocket 106 as rotary valve 64 rotates to align inlet 80 with fluidpocket 106.

The motive fluid contained in the lower portion of density separationchamber 91 travels to inlet 79 and enters fluid pocket 105 as rotaryvalve 64 rotates to align inlets 79 and fluid pocket 105. Rotary valve64 continues its axial movement effectively isolating fluid pockets 105and 106. As the rotation of valve 64 continues, pockets 105 and 106 comeinto alignment only with expansion chamber 77 via port 69. As the fluidpockets 105 and 106 align with port 69 the motive fluid contained inpocket 105 and the dense heat transfer fluid contained in pocket 106make direct contact resulting in a thermal reaction between the motivefluid and the dense heat transfer fluid causing a rapid phase change ofthe motive fluid and a corresponding increase in pressure in theexpansion chamber 77. Dense heat transfer fluid flows from expansionchamber 77 via pulse eliminator/accumulator 76 and then intorecirculation pump 75 and then into heat exchanger 73 to continue thecycle as described above.

A partial density separation of the motive fluid and the dense heattransfer fluid takes place in the expansion chamber 77 resulting in themotive fluid leaving expansion chamber 77 via port 110 in asubstantially vapour phase and under high pressure. Motive fluid leavesexpansion chamber 77 and travels through pulse eliminator/accumulator 83and then into turbine 110. Work is extracted via a work extractingmechanism that extracts work from the pressurized fluids by way ofpressure let down, such as, turbine 110 via electrical generator 111 orsimilar machinery. As the motive fluid passed through turbine 110 andwork is extracted, pressure and temperature are reduced as mechanicalwork is performed by turbine 110 on electrical generator 111. The motivefluid then exits turbine 110 and enters density separation chamber 91 ina multiphase condition being a mixture of liquid and gas as representedby 97. Cooling and return to 100% liquid condition takes place as themotive fluid passed through condenser 87 and leaves condenser 87 as 100%liquid phase 90. Energy is removed during the condensing process bycondenser 87 which circulates a cooling fluid through the condenser viacondenser inlet 113 and condenser outlet 114. The cooling medium can beair, water, refrigerant or other low temperature fluids coming fromunrelated process. At this point the motive fluid is at the bottom ofits temperature and pressure cycle and is ready to continue via port 79and into fluid pocket 105.

Referring to FIG. 9, there is shown a process flow diagram of anemission less power extraction system in accordance with anotherembodiment of the present invention system utilizing a multi fluiddirect contact pulsating cycle and employing an external high-pressurerotary injection valve in conjunction with a piston expansion engine forthe conversion of thermal energy into electricity from sources such assolar, wind, waste heat, geothermal, biomass oxidation according to thepresent invention. Work is extracted via a work extracting mechanismthat extracts work from the pressurized fluids by way of pressure letdown, in this case, the reciprocating pistons in the piston expansionengine that turn an output shaft.

The system is like that shown in FIG. 8 except that the motive fluidafter the pulsation damper 83 is flowed through valve 92 and into pistonchamber 94.

The timing of inlet valve 92 and exhaust valve 96 may be controlledelectronically, via a camshaft and valves or other methods such as therotary valve detailed in FIGS. 14-17. Power extraction is accomplishedby operating two cycles with a reciprocating expansion engine. Duringthe power cycle, when piston reaches top dead centre, exhaust valve 96closes and inlet valve 92 opens allowing high pressure motive fluid flowfrom expansion chamber 77 to enter the piston cavity via port 93. Inletvalve 92 can remain open for a portion of the downward travel of thepiston or it can be closed at any point in the downward travel of thepiston depending on the level of pressure drop and power extractiondesired. The high-pressure motive fluid drives the piston downwardturning a crankshaft and power extraction device attached to thatcrankshaft of some sort know in the industry. As the piston reaches thebottom of the stroke valve 92 is closed and exhaust valve 96 is opened.As the piston travels upward the cooled and lower pressure motive fluidis expelled from the piston cavity and travels through exhaust valve 96into density separation chamber 91 where the motive fluid, 88, iscondensed and ready to continue to the top of the cycle as describedabove.

Referring to FIGS. 10-13, there is shown various views of an externalhigh-pressure rotary injection valve. These figures show the externalhigh-pressure rotary injection valve in three distinct parts of therotational cycle of the valve.

FIG. 10 shows an end view of an external high-pressure rotary injectionvalve in the filling phase of its rotation. Central shaft, 64 ispositioned to align inlet port 66 with fluid pocket 68 and is beingfilled with either motive fluid or dense heat transfer fluid.

FIG. 11 shows an end view of an external high-pressure rotary injectionvalve in the injection phase of its rotation. Central shaft, 64 ispositioned to align fluid pocket 68 with the inlet port to expansionchamber 69, causing fluid pocket 68 to inject either motive fluid ordense heat transfer fluid into expansion chamber via inlet port 69.

FIG. 12 shows an end view of an external high-pressure rotary injectionvalve in the exhaust phase of its rotation. Central shaft, 64 ispositioned to align fluid pocket 68 with the exhaust port 65 allowingany residual fluid remaining motive fluid or dense heat transfer fluidremaining in fluid pocket 68 to be emptied into density separationchamber 91 via inlet port 69.

FIG. 13 shows an end view of an external high-pressure rotary injectionvalve showing one example of three possible positions in the cycle wherethe fluid pockets are isolated or sealed from any communication or flow.Central shaft, 64 is positioned to so that fluid pocket 68 is notaligned with either of ports 65, 66 or 69 and is isolated or sealed.This condition occurs three times during each rotation of the valvespool.

Referring to FIG. 14-16, there is shown end and side view diagrams of anemission-less power extraction system in accordance with anotherembodiment of the present invention system utilizing a multi fluiddirect contact pulsating cycle and employing an external high-pressurerotary injection valve in conjunction with a reciprocating pistonexpander in four different phases of a rotational cycle.

FIG. 14 shows an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander in the exhaust andpocket fill phase of the rotational cycle. Piston 103 is travelingupward in piston bore 104 and exhaust port 100 is in is communicationwith exhaust pocket 109 allowing the mixture of motive fluid and denseheat transfer fluid resident in the piston bore to exhaust. At the sametime, shaft 99 is positioned so that fluid pockets 105 and 106 are a incommunication with inlet ports 98 and 107 respectively. Fluid pockets105 and 106 are being filled with motive fluid and dense heat transferfluid.

FIG. 15 shows an external high-pressure rotary injection valve inconjunction with a reciprocating piston expander in the power phase ofthe rotational cycle. Piston 103 is traveling downward in piston boreand valve shaft 99 is positioned so that fluid pockets 105 and 106 andin fluid communication with inlet ports 101 and 102 allowing the motivefluid and the dense heat transfer fluid to come into direct contact witheach other causing a rapid thermal reaction resulting in a rapidpressure increase in piston chamber 104 effectively driving the pistondownward and delivering work to the crankshaft (not shown). Exhaust port100 is closed off and exhaust pocket 109 is sealed as well and there isno flow coming in via inlet ports 98 and 107.

FIG. 16 is very similar to FIG. 15 and shows an external high-pressurerotary injection valve in conjunction with a reciprocating pistonexpander in the power/expansion phase of the rotational cycle. Piston103 is traveling downward in piston bore 104 with useful work beingextracted via the crankshaft (not shown). Valve shaft 99 is positionedso that fluid pockets 105 and 106 are at the final stages of dischargingtheir contents and are remain in fluid communication with inlet ports101 and 102 allowing any residual motive fluid and dense heat transferfluid to exit the fluid pockets and into the piston chamber 104. Inpiston chamber 104 the expansion of the mixture of motive fluid anddense heat transfer fluid continues to drive the piston downwarddelivering work to the crankshaft (not shown). Exhaust port 100 andexhaust pocket 109 are isolated and closed.

FIG. 17 is very similar to FIG. 14 and shows an external high-pressurerotary injection valve in conjunction with a reciprocating pistonexpander in the beginning of the exhaust and pocket fill phase of therotational cycle. Piston 103 is traveling upward in piston bore 104 andexhaust port 100 is in communication with exhaust pocket 109 allowingthe cooled and lower pressure mixture of motive fluid and dense heattransfer fluid resident in the piston bore to exhaust. At the same time,shaft 99 is positioned so that fluid pockets 105 and 106 are justbeginning to be in communication with inlet ports 98 and 107respectively. Fluid pockets 105 and 106 are being filled with motivefluid and dense heat transfer fluid.

The key feature/function of the high pressure rotary injection valve isto facilitate the injection of the two or more fluids of which at leastone of the fluids is a motive fluid and one of the fluids is a denseheat transfer fluid where at the low pressure side of the rotation as inFIG. 16 each fluid enters into the rotary valve pockets 105 and 106 inisolation from the other fluid allowing the respective fluids tomaintain unrelated pressures and temperatures. As the Rotary Valve turnsthrough its axis the fluid pockets come into alignment with ports 101and 101 and come into open communication with the piston bore 104 wherea rapid and high pressure mixture takes place causing a thermal reactionbetween the motive fluid and the dense heat transfer fluid with rapidexpansion taking place as shown in FIGS. 14 and 15, causing the piston104 to travel downward causing work on the engine crankshaft. The rotaryvalve then continues in its rotation causing pockets 105 and 105 totravel past openings 101 and 102 to coincide with the piston 103reaching bottom dead center in its travel and at the working fluidslowest pressure and temperature conditions. Pockets 105 and 106, nowcontaining residual amounts of the combined fluid mixture and at thelowest pressure point of the cycle, become sealed and cease to be incommunication with either inlet ports 98 and 97 or with outlet ports 101and 102. At this point the exhaust 109 and 65 begins to open providingopen communication and flow between the piston bore 104 and exhaust port100 allowing for the piston bore to be emptied of the now cooled and lowpressure working fluid mixture as piston 103 rise upward as in FIG. 13.As the Rotary valve continues in its rotation exhaust valve 109 is timedsuch that it remains open to exhaust port 65 and 109 until piston 103reaches top dead center. Also during this travel, fluid pockets 105 and106 have traveled past fluid inlets 98 and 107 as in FIG. 13 and FIG. 9,allowing for the fluid pockets to receive the desired amount of motivefluid and dense heat transfer fluid and to then travel into opencommunication with ports 101 and 101 allowing for open communicationwith the piston Bore 104 where the two fluids come into contact witheach other causing a rapid and high pressure thermal reaction to takeplace between the motive fluid and the dense heat transfer fluid withrapid expansion taking place as the motive fluid changes phase as shownin FIGS. 14 and 15, causing the piston 104 to travel downward causingwork on the engine crankshaft.

Selection Criteria for the Motive Fluid and the Dense Heat TransferFluid.

The motive fluid is chosen based on phase change characteristics.Examples of motive fluids are fluids such as CO2, R134a, R410A and R32.The key features of motive fluid are:

-   -   a relatively low temperature boiling point/phase change below        212° F. with relatively high vapor pressure at temperature range        between 120° F. and 212° F.;    -   condensing temperature range within 32° F. and 120° F.; and    -   low specific gravity to facility density separation from dense        heat transfer fluid where the condensed motive fluid will        separate and float on top of the dense heat transfer fluid when        combined in a storage or settling chamber.

The dense heat transfer fluids are chosen based on desirable phasechange characteristics, density, specific heat capacity. Fluids such asethylene glycol and 1,2,3-propanetriol (glycerol) offer desirablecharacteristic. Key features of dense heat transfer fluid are:

-   -   A relatively high temperature boiling point/phase change above        212° F. The dense heat transfer fluid should not phase change        during the complete cycle but simply absorb heat energy and        transfer that heat energy to the motive fluid.    -   A high specific gravity beyond that of the motive fluid to        facility density separation from motive fluid. For example,        glycerol has a specific gravity of 1.26 and ethylene glycol has        a specific gravity of 1.135 at standard temperatures.    -   A high specific heat capacity.

The motive fluid and the dense heat transfer fluid interact as follows:During the cycle the dense heat transfer fluid is heated to desiredupper temperature range of the cycle by an external heat source; themotive fluid is condensed to liquid phase by transferring heat energyinto the refrigeration fluid loop as in the detailed description. Themotive fluid and dense heat transfer fluid are then combined in aenclosed space such as a pressure chamber such as in accumulator 5 inFIG. 1 or as in a external mixing chamber 77 in FIG. 8 or as in a pistonchamber as in 104 in FIG. 13-16. The mass ratio of the dense heattransfer fluid to motive fluid is metered into the enclosed space asrequired that when combined with the motive fluid the heat energyrequired to cause a phase change in the motive fluid is transferred byconduction from the dense heat transfer fluid to the motive fluidcausing a phase change in the motive fluid and a temperature reductionin the dense heat transfer fluid. An equilibrium of temperature is reachvery quickly resulting in the motive fluid being completely changed intogaseous phase and the dense heat transfer fluid remaining in a liquidphase but at a lower temperature. The result of the above reaction isthat the expansion that takes place by the motive fluid changing phasecauses a dramatic and rapid increase in pressure in the confined spaceallowing useful work to be extracted by various extraction methodsdescribed herein.

While specific embodiments of the invention have been described, suchembodiments are illustrative of the invention only and should not betaken as limiting its scope. In light of the present disclosure, manymodifications will occur to those skilled in the art to which theinvention relates, and the invention, therefore, should be construedaccordingly.

1. An apparatus for extracting useful work or electricity from low grade thermal sources comprising: a chamber; a source of heated dense heat transfer fluid in communication with the chamber; a source of motive fluid in communication with the chamber, wherein the motive fluid comprises a liquid phase; a flow control mechanism cooperating with the source of heated dense heat transfer fluid and with the source of motive fluid to deliver said fluids into the chamber in a manner that said fluids come into direct contact with each other in the chamber to effect a phase change of the motive fluid from liquid to gas to increase the pressure within the chamber to yield pressurized fluids; and a work extracting mechanism in communication with the chamber that extracts work from the pressurized fluids by way of pressure let down.
 2. The apparatus as claimed in claim 1 further comprising a density separator downstream of the work extracting mechanism to separate the dense heat transfer fluid from the motive fluid.
 3. The apparatus as claimed in any one of claims 1 and 2, further comprising a condenser downstream of the work extracting mechanism to condense the motive fluid into liquid phase.
 4. The apparatus as claimed in any one of claims 1-3, further comprising a first recirculating conduit to the source of motive fluid.
 5. The apparatus as claimed in any one of claims 1-4, further comprising a second recirculating conduit to recirculate the dense heat transfer fluid to the source of heated dense heat transfer fluid.
 6. The apparatus as claimed in any one of claims 1-5, further comprising a heat exchanger communicating with a thermal source and the second recirculating conduit to transfer heat energy from the thermal source to the dense heat transfer fluid to provide the source of heated dense heat transfer fluid. The apparatus as claimed in any one of claims 1-6, wherein the flow control mechanism comprises a rotary valve having a first pocket to receive a volume of heated dense heat transfer fluid and a second pocket to receive a volume of motive fluid, the rotary valve being operable to expose the first pocket and the second pocket to the chamber to bring said fluids into direct contact.
 8. The apparatus as claimed in any one of claims 1-7, wherein the work extracting mechanism comprises a turbine that is driven by the pressurized fluids to rotate an output shaft to produce work.
 9. The apparatus as claimed in any one of claims 1-7, wherein the work extracting mechanism comprises a reciprocating piston that is driven by the pressurized fluids to rotate an output shaft to produce work.
 10. A method of extracting useful work or electricity from low grade thermal sources comprising the steps of: a. heating a dense heat transfer fluid using heat from a thermal source; b. mixing the heated dense heat transfer fluid with a motive fluid comprising a liquid phase in a chamber to effect a phase change of the motive fluid from liquid to gas to increase the pressure within the chamber and yield pressurized fluids; and c. using the energy of the pressurized fluids to produce useful work.
 11. The method as claimed in claim 10, wherein the dense transfer fluid is heated in step a. to a temperature of about 34° F. to about 210° F.
 12. The method of any one of claims 10-11, further comprising the step of cooling the motive fluid after step c. to effect a phase change of the motive fluid to liquid. 